Crossroads Systems, Inc.

Thomas W Bucht

Steve King

Chiayin Mao

Michael Nelson

A method for decreasing routing latency of a switching platform comprises identifying ports which have changed their operational state and modifying the port polling code associated with the respective ports so that operational ports are polled for frames to be routed, while non-operational ports are not polled. In one embodiment, the method is implemented in a fiber channel switch. Non-operational ports are identified as having operational states below a pre-determined threshold level of functionality. The polling code for the ports is modified while polling operations are carried out in the switch. The code for a newly operational port is modified by copying into the code one or more instructions that poll the port for a frame and routes the frame. The code for a newly non-operational port is modified by copying into the code a branch instruction that bypasses the remainder of the polling code for the port. The frame routing latency of the switch is reduced because ports which are non-operational and will not produce frames are not polled.

Method and system for decreasing routing latency for switching platforms with variable configuration

A system and method for storing header information in parallel with corresponding frames of data, wherein the frames of data are stored in a first-in-first-out buffer and wherein the header information is accessed to make routing decisions for the frames of data while avoiding having to read the frames out of the buffer. In one embodiment, this buffer system is implemented in a port of a network switch. Receive logic in the port stores frames of data in the storage elements of a FIFO buffer and concurrently snoops on the frame data to obtain header information. The header information is stored in a buffer separate from the FIFO that stores the frames. The header information can be read from the header buffer rather than the frame buffer. A routing decision for each frame can be made before a previous frame is completely read out of the frame FIFO, hence before the corresponding frame is ready to be transmitted. A timer may also be associated with each header in the header buffer so that it can be determined when frames are stale and must be discarded.

System and method for storing frame header data

A system and method for compensating for differences between a recovered receive clock and an internal transmit clock in an elastic buffer and thereby preventing corruption of data. In one embodiment, the system comprises a circularly accessed buffer coupled to read and write logic. The read and write logic read and write to locations within the circular buffer as indicated by respective read and write pointers. The system further comprises control logic which compares the pointers to determine whether the buffer is approaching an underflow or overflow condition and adds or deletes fill words between frames of data to compensate for the underflow or overflow condition. In one embodiment, the system includes fill word logic which is configured to add a fill word bit to each received word and to set or clear the fill word bit to indicate whether or not the corresponding word is a fill word.

System and method for jitter compensation in data transfers

A method for decreasing routing latency of a switching platform comprises identifying ports which have changed their operational state and modifying the port polling code associated with the respective ports so that operational ports are polled for frames to be routed, while non-operational ports are not polled. In one embodiment, the method is implemented in a fibre channel switch. Non-operational ports are identified as having operational states below a pre-determined threshold level of functionality. The polling code for the ports is modified while polling operations are carried out in the switch. The code for a newly operational port is modified by copying into the code one or more instructions that poll the port for a frame and routes the frame. The code for a newly non-operational port is modified by copying into the code a branch instruction that bypasses the remainder of the polling code for the port. The frame routing latency of the switch is reduced because ports which are non-operational and will not produce frames are not polled.

A method and system for decoding 8B/10B data is provided. In one embodiment, the method includes the steps of determining the presence of one of a plurality of predetermined data sequences within a first portion of a data word, translating the predetermined data sequences into representative signals (flags) having a smaller aggregate data width than the first portion of the data word, and providing the representative signals together with remaining portions of the data word to a logic block for decoding. This embodiment of the present method allows the encoded data to be decoded using limited-width decoders, allows first and second portions of each encoded data word to be decoded concurrently, and allows the decoding of the encoded data words to be pipelined to increase the throughput of the decoder.

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Hillsboro, OR, United States of America

Thomas W Bucht